Another Look at Sibship Structure and Educational Achievements

Studies have shown negative correlations both between number of siblings and educational achievement and between number of siblings and cognitive ability. These findings are consistent with the Resource Dilution Hypothesis, the Quantity-Quality Trade-off Theory, and the Confluence Model. However, recently some scholars have questioned the causal interpretations of the correlations and have simulated quasi-experimental studies to test the hypothesis that it is largely spurious. The results of these tests are inconsistent so far.

This paper attempts to further the understanding of the sibship size effect and its causality.  We employ a retrospective life history data set on some 2000 Jewish Israeli men who were born in 1954 and interviewed while in their mid-twenties. The database includes information on several educational and cognitive outcomes measured at different ages; socio-economic background variables, and detailed sibship and household composition measures. We use fixed-effect models to evaluate the causality of the sibship-achievement association. The availability of detailed histories of household composition allows us to estimate the effects of siblings present (in the household) at different stages of the life course on cognitive and educational outcomes. This is a more precise measure than the measures that have been common in the literature so far. 

Preliminary results show that the number of sibling present in the household at ages that precede the measures of outcomes is more detrimental to its achievement than the overall sibship size.